The following discussion of the background to the invention is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was, in Australia, published, known or part of the common general knowledge as at the priority date established by the present application.
All spectroscopic based elemental analysers (except those that use X-ray techniques) require a gas supply, for example acetylene and nitrous oxide for flame atomic absorption spectroscopy (FAAS), or argon for inductively coupled plasma (ICP) emission or mass spectrometry. For a microwave induced plasma spectroscopic source, a preferred plasma forming gas is nitrogen, as disclosed in the applicant's International application No. PCT/AU01/00805 (WO 02/04930 A1) at pages 9-10 (which has been granted as U.S. Pat. No. 6,683,272 B2).
Providing a gas supply for spectroscopy systems is typically very expensive, for example the annual gas supply costs can amount to as much as the initial purchase price of a spectroscopy instrument and possibly be even higher if the gas has to be supplied to a remote location. A significant factor in this cost is the high purity customarily required of the supplied gas. For example, commercially supplied nitrogen is typically specified as containing less than 0.1% by volume of oxygen and argon together.